Arrangement of cutters in barking machines of drum type



5. VALO ARRANGEMENT OF CUTTERS IN BARKING MACHINES OF DRUM TYPE Filed Dec. 10, 196-3 United States Patent 3,221,785 ARRANGEMENT 0F CUTTERS IN BG MAC 0F DRUM TYPE Bruno Valo, Lohja, Finland Filed Dec. 10, 1963, Ser. No. 329,506 3 Claims. (Cl. 144208) This invention relates to an arrangement of cutters in barking machines of drum type, in which the logs to be barked are fed lengthwise through a rotating drum, in which drum there are pivotally mounted resiliently engaged barking arms, directed towards the axis of the drum, the ends of which arms are provided with barking cutters which are pressed against the surface of the log to be barked.

It is known that in barking machines of this kind, one or several of the arms provided with barking cutters can be replaced with corresponding arms provided with cutting knives, whereby the barking of the log is facilitated, because the knives prevent forming of continuous strips of bark along the log surface during operation. These knives have heretofore been arranged in the same plane substantially perpendicular to the axis of rotation of the drum (the moving track of the log) as the barking cutters, which arrangement has many disadvantages.

Since in cutting arrangements of the aforesaid type the moving track for the knife on the log surface always is formed between the moving track of both of the adjacent barking cutters, it can result inespecially when barking a log in which the bark is rather loose and easily removed-that the knife cuts right through the bark, dividing the bark stripe, which the following barking cutter is intended to strip off in two halves whereby some portions of the stripe may remain unremoved on the log owing to the fact that the strip is no longer integral in the transverse direction of the strip but is divided in two halves. As will appear from the following description, the advantages offered by the use of such special cutting knives cannot effectively be utilized in known barking devices.

The present invention has for an object the elimination of the above stated disadvantages, and the cutter arrangement according to the invention is characterized in that there is a relation to the direction of movement of the log in front of each barking cutter a pre-cutter carried by an arm pivotally mounted similar to the barking cutters in the drum, said pre-cutters being arranged to operate in a plane substantially perpendicular to said direction of movement and at such a distance from the plane formed by said barking cutters that the moving track of each barking cutter substantially follows the moving track of the corresponding pre-cutter along the surface of the log being barked.

According to the present invention there is produced a cutting arrangement by which the barking of logs becomes more effective and reliable than with the known arrangements owing to the following facts. According to the invention there is moving in front of the actual barking cutter a pre-cutter mainly along the same track as the actual cutter, which pre-cutter strips off the bark so that there is formed a narrow notch. This operation is of great importance especially when barking dry or icy logs, because the pre-cutter owing to its narrow shape easily cuts its way through the bark and loosens a narrow strip from it. Thus the actual broader barking cutter that follows does not have to cut through the bark, which would require great working power due to the width of the cutter, whereby the barking cutter can effect a shaving operation to remove the bark. In the barking of wet logs, in which the bark layer is fairly tenacious, the said narrow pre-cutter can be formed as a sharp cutting knife, which more easily cuts through the wet bark. By arranging the actual barking cutters and the cooperating pre-cutters so that they are moving substantially along a mutual moving track, the pre-cutters will not cut the stripes of bark intended to be removed by the actual barking cutters following each pre-cutter in separate parts, but said stripes of bark can be removed by the actual barking cutters as an integral stripe. By this means the skin flakes are at the same time prevented from being stripped off as long, continuous strips along the log. As the actual barking cutters according to the invention perform the barking mainly by means of shaving, the cutters need not be kept very sharp, it being sufiicient that the pre-cutters be kept well sharpened. By this means the keeping of the cutters in proper working condition is reduced by more than half of the time required by the known arrangements.

The invention will now be further described below with reference to the accompanying drawing, in which FIGURE 1 shows a perspective view of an embodiment of the cutting arrangement according to the invention, and

FIGURE 2 shows a partial view of a cutting arrangement according to FIG. 1, in the direction shown by the arrow II in FIG. 1.

The cutting arrangement shown in the drawing has four actual barking arms 1, which at their outer ends are pivoted equally spaced in the drum of a barking machine of drum type (not shown). The mounting of the pivoted arms in the barking drum and the engagement of the arms can be made for example in accordance with the construction described in the US. patent application No. 95,727, now Patent No. 3,115,167. The ends of the barking arms directed towards the central axis of the drum are provided with shaped barking cutters 2, which in a known manner are arranged to lie in the same plane 4 (FIG. 2) perpendicular to the axis 3 of rotation of the drum.

According to the invention the cutting arrangement further comprises four pre-cutting arms 5, which like the barking arms 1 are pivotally mounted in the drum of the barking machine between the barking arms 1. The ends of the pre-cutting arms 5 directed towards the center of the drum are shaped as narrow pre-cutting knives 6, which all are arranged to lie in the same plane 7 perpendicular to the axis of rotation of the drum, the said plane 7 lying in front of and at some distance from the plane 4 of the barking arms 2 in relation to the feeding direction 9 of the log 8 passing lengthwise through the drum for the barking operation. The pre-cutting knives 6 are here displaced in relation to the actual barking cutters 2 at such a distance from cutters 2, i.e. said plane 7 is at such distance in front of plane 4, that the moving tracks, traced by the actual barking cutter and the corresponding pre-cutting knife along the surface of the log fed through the drum, always :coincide, ie the barking cutter 2 follows the corresponding pre-cutting knife 6 substantially along its moving track on the surface of the log.

This is illustrated in FIG. 1, in which the log 8 to be barked is in a position in which the actual barking cutter 2 just has been displaced upon the log surface at the starting phase of the operation. Before this the precutting knife 6 has cut into the log surface a narrow notch 10, and the moving track which these cutters hereafter follow on the surface of the log is designated by 10'. As appears from FIG. 1, the barking cutter 2 which follows along said track will due to its broader size strip off the remaining broader stripe of bark 11 by means of a shaving operation.

According to a preferred embodiment of the invention,

the barking arms and the pre-cutting arms are pivoted on the drum in an alternating manner equally spaced, and the cutting portions of the pre-cutting arms are bent to such distance from the plane formed by the-barking cutters, that the moving tracks of the pre-cutting knives substantially coincide with the corresponding moving tracks of the barking arms on the log surface. By this construction there is attained the advantage that all the bearings in the drum, for both the actual barking arms as well as for the pre-cutting arms, can be of the same construction, whereby in each bearing there can be fixed either a barking arm or a pre-cutting arm without the necessity of spacer blocks or the like.

The expression the moving tracks of the actual barking cutters coincide with the moving tracks of the corresponding pre-cutting knives is of course not to be understood that the actual barking cutter should even have to shave clean the notches cut in the bark by the pre-cutting knives, but in general, that both the barking cutter and the corresponding pre-cutting knife substantially follow along adjacent surface areas.

The drawing and the corresponding specification are of course only to be understood as an illustration of the inventive idea of the invention. As to its details the arrangement of cutters according to the invention can therefore vary considerably within the scope and limits of the claims.

What I claim is:

1. An arrangement of cutters in barking machines of drum type, in which the logs to be barked are fed lengthwise through a rotating drum, in which drum there are pivotally mounted resiliently engaged barking arms directed towards the axis of the drum, the ends of which arms are provided with barking cutters which are pressing against the surface of the log to be barked, characterized in that there is in relation to the direction of movement of the log in front of each barking cutter a pre-cutter carried by an arm pivotally mounted similarly as the barking cutters in the drum, said pre-cutters being arranged to operate in a plane substantially perpendicular to said direction of movement and at such a distance from the plane formed by said barking cutters that the moving track of each barking cutter substantially follows the moving track of the corresponding pre-cutter along the surface of the log being barked.

2. An arrangement of cutters as claimed in claim 1, wherein the barking arms and the pre-cutting arms are pivoted alternatingly onto the drum in equally spaced relation, the cutter portions of the pro-cutting arms being bent at such distance from the plane formed by the barking cutters, that the moving tracks of the pre-cutters substantially coincide with the corresponding moving tracks of the barking arms on the log surface.

3. An arrangement of cutters as claimed in claim 1 wherein each pre-cutter consists of a narrow cutter, and each of the barking cutters consists of a broader cutter.

References Cited by the Examiner UNITED STATES PATENTS 2,860,672 11/1958 Brundell et all. 3,119,422 1/1964 Brown.

WILLIAM W. DYER, JR., Primary Examiner. 

1. AN ARRANGEMENT OF CUTTERS IN BARKING MACHINES OF DRUM TYPE, IN WHICH THE LOGS TO BE BARKED ARE FED LENGTHWISE THROUGH A ROTATING DRUM, IN WHICH DRUM THERE ARE PIVOTALLY MOUNTED RESILIENTLY ENGAGED BARKING ARMS DIFECTED TOWARDS THE AXIS OF THE DRUM, THE ENDS OF WHICH ARMS ARE PROVIDED WITH BARKING CUTTERS WHICH ARE PRESSING AGAINST THE SURFACE OF THE LOG TO BE BARKED, CHARACTERIZED IN THAT THERE IS IN RELATION TO THE DIRECTION OF MOVEMENT OF THE LOG IN FRONT OF EACH BARKING CUTER A PRE-CUTTER CARRIED BY AN ARM PIVOTALLY MOUNTED SIMILARLY AS THE BARKING CUTTERS IN THE DRUM, SAID PRE-CUTTERS BEING ARRANGED TO OPERATE IN A PLANE SUBSTANTIALLY PERPENDICULAR TO SAID DIRECTION OF MOVEMENT AND AT SUCH A DISTANCE FROM THE PLANE FORMED BY SAID BARKING CUTTERS THAT THE MOVING TRACK OF EACH BARKING CUTTER SUBSTANTIALLY FOLLOWS THE MOVING TRACK OF THE CORRESPONDING PRE-CUTTER ALONG THE SURFACE OF THE LOG BEING BARKED. 